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June 15, 2016

HOW YOUR SENSE OF TOUCH WORKS

Most people understand the sense of touch in a general sense—after all, we’ve all felt another person’s hand on our arm, or ran our hands over smooth or rough surfaces. However, the sense of touch is far more broad and comprehensive, including more sensory perception than simply “feeling” on our skin.

Your sense of touch is how your body perceives temperature, pressure, pain, and stretching. Touch is not only perceived by skin, but includes receptors in the muscles as well. This is because touch serves two vital purposes: one, it allows us to engage with our environment more accurately. Imagine how well you could survive without your ability to feel heat—one day in the kitchen could cause you serious injury.

The second vital purpose of touch is to provide an internal signal of how well your brain’s “orders” are being followed. For example, if your brain sends a signal to your hand to make a fist, your sense of touch provides an immediate return signal letting you know that your hand is in a fist. This creates a feedback cycle that facilitates better communication between your brain’s impulses and the body’s response.

TOUCH RECEPTORS

Your sense of touch depends on a multitude of receptors. The first group of receptors are contained in your skin. While not often regarded as an organ by everyday people, your skin is actually the largest organ of your body. It contains five different types of touch receptors in your skin, each responsible for a different type of signal or group of signals, to update your brain on the status of its largest organ.

Pacinian corpuscles: Mostly high frequency vibration signals, joint position changes, and rapid changing pressure.

Meissner’s corpuscles: Light touch, such as in our lips and finger pads. Vibration and stretch. Helps us feel detailed texture, like braille writing.

Ruffini corpuscles: Touch and joint position. Helps us determine if something is moving on our skin, such as when something is sliding out of our hand.

Merkel cells: Deep touch, pressure, and position. Helps feel shapes and edges.

Free nerve endings: These receptors are the most numerous, and are called “polymodal,” meaning that they have multiple functions. They perceive pain, temperature, pressure, stretch, and itch signals.

Each of these receptors are “multi-modal receptors,” or each detect multiple types of signals at once. For example, if you were to press a pin on your skin right now, you would feel both pain and pressure simultaneously (although your pain might be given more attention than pressure in the moment).

The second group of touch receptors is in the muscles. These include two types: muscle spindle fibers and golgi tendon organs. Muscle spindle fibers are located in the belly of the muscle and detect the length of the muscle and the rate of stretch. Golgi tendon organs are located in the tendons of the muscles (where it attaches to the bone). It detects the degree and rate of stretch of our muscles.

What’s the purpose of these receptors?

Simple: to keep us from ripping our muscles from our bones. The discomfort we feel while stretching is the body’s way of letting us know we are approaching its mechanical limits. Each of our receptors, both skin and muscle, transduce mechanical and thermal signals into electrical ones, allowing our brain to respond to the environment around us and our body’s positioning in 3D space. But what happen if the brain is misinterpreting these messages?

HOW TOUCH INTEGRATES WITH THE BRAIN

Our work involves brain function, so how does touch factor into that? In an earlier post about the parietal lobe, we discussed the “sensory homunculus.” As a reminder, the sensory homunculus is the part of your brain that corresponds to the touch receptors of the body. The more receptors there are in parts of your body, the more your brain will perceive those parts.

(This is why models of your sensory homunculus often have enormous hands, lips, feet, and eyes—there are a larger number of receptors in these areas).

Signals from touch receptors travel along peripheral nerves, which connect to your spine. The spine then directs the signals to the brain, where the signals will be processed in the corresponding parts of the brain. Where this meets clinical application is how our ReceptorBased® rehabilitation specialists alter the amount of information traveling from receptors to the parietal lobe.

WHAT DOES THIS MEAN FOR OUR CLIENTS?

So, this is all good information, but how does it actually help our clients improve brain function?

Let’s say we have a client who has an issue with body perception. Their spatial awareness or coordination may be a result of parietal lobe dysfunction. You cannot navigate the world if you cannot accurately process the location of your body. Doctors at Plasticity Brain Centers stimulate touch receptors using differing modalities (types of signals) in order to restore function to parts of the parietal lobe. You might already be familiar with a type of therapy that specializes in this area: massage.

Massage therapy may use stretch and pressure stimulation in order to influence how the brain receives signals from those muscles. Muscles are like guitar strings. If a muscle is too tight, when “plucked” (stimulated), it will “buzz” far too loud (sending too much information to the brain). These signals may manifest as soreness, pain, tension, discomfort, or incoordination.

However, the opposite problem can be true as well—if too loose, muscles may not send enough information to the brain.

Whatever the issue may be, our therapists can use stretch, heat, ice, vibration, and pressure in order to change the amount of information sent by your body parts to the brain. Controlling the flow of the signals can change the way the brain functions because it will adapt to the information it receives. In this way, touch-based modalities can improve brain function.

For instance, these therapies can provide relief by decreasing the effect of pain syndromes. If your hand is feeling a great deal of pain on a constant basis, decreasing the information flow from the hand to the brain would also decrease the amount of pain you would perceive. As our parietal lobe blog noted, these therapies can also be effective for patients who have missing limbs and experience phantom pains.

This approach is not just for those with brain injury, either—high-level athletes have benefitted from the way our therapies improve coordination and bodily awareness. Touch-based therapies could improve the efficiency of the brain with regard to spatial awareness, body positioning, and coordination to enhance performance naturally and effectively.

If you, a loved one, or a patient has issues with spatial awareness or chronic pain, or is looking to improve coordination, our ReceptorBased® rehabilitation specialists can help. Our therapies, all taught by the Carrick Institute, can help strengthen brain function quickly and effectively. Call today for more information.

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